My thoughts lately have become somewhat distilled.
Save or die
Saving throws are the chance to avoid a consequence; All save or die traps are actually just die traps. But the first time that happened, someone probably felt like a dick, so saving throw.
Anyone who complains should be listened to and the save should be removed.
Natural or Magical
A great many things are not improved by improvement. Why give players a system where they can be more 'skilled' in searching or surprise when scaling those systems causes problems?
Mundane systems (like surprise, trap setting off, drowning chance, door opening) that are modified situationally (Strength, armor worn) ground the game making the world more threatening and real.
Constant Improvement in Both Difficulty and Skill is Illusionary
It is also pretty trivial common knowledge now that subjective improvement has many consequences over objective improvement. A ninth level fighter saves on a 2 because he has a lot of opportunities to face instant death. If he has the same 60% fail rate he does at first level, then he isn't really ninth level now is he?
This goes double if you turn it around for monsters. Wizards push their save and monsters succumb. Trivial common knowledge
Games need to be designed, and since nobody really knew what gamers were doing with their home campaigns, this was hard.
An example. I have this post here where I completely trash the appraisal skill.
I run +Numenhalla here where appraisal is a key skill on a very short list of skills.
Why? Because "How do we get the treasure out of the dungeon?" is a key pillar of play. So for that game design a mechanic of, "Do we know how much this is worth?" is crucial.
This results in systems with too many skills. The skill list should be an indicator of what the players are going to be spending time doing in the game, not a cohesive list of everything that might be possible for a player to try. Fewer choices are also better for the players.